Though excitable and never particularly one not to show her emotions, Tonks could bottle it in when she needed to. So when Remus made his guess, she was nodding. It could be right. She certainly had wanted to be an Auror desperately. Of course, older Remus would have seen right through her statements and known all too well that Tonks would not have been Head Girl material and would have had an innocent laugh as such. But younger Remus, clever as he was, wouldn't take too long at all to come to the same conclusion. Tonks was relatively (read very) sure of it.
She listened to Rose's logic with the same ambivalent agreeance, though looked mock hurt when Rose said she didn't seem Head Girl material. "I'm wounded, Rose Tyler! Positively wounded!" But she was grinning and motioning her head as if to say 'well..' Then nudged Remus' foot with her own playfully.
"Rose got this one. It was actually makin' fun of one instructor that saved my ass in the end. The other one, Moody, thought it was ace how I got Dawlish spot on." And so the girl who whizzed through Disguise proved her worth..even if Stealth came a little harder.